One problem that the present invention aims to solve is the following. In most large towns tap water is produced in large plants and transported to the consumers through a system of pipes. To protect the water from infection risks during transportation a certain amount of chlorine is normally added before the clean water leaves the plant.
A certain amount of this chlorine is consumed on the way and a certain amount remains in the water when it reaches the consumers. The reason for the addition of chlorine is for it to break down potentially dangerous organic pollutants in the pipes. When this occurs chlorinated hydrocarbons such as chloroform and bromoform are produced. These substances are therefore also present to a certain extent in the water that reaches the consumers.
Even though the quantities of chlorine and chlorinated hydrocarbons are low in the water, it is known that both types of the compounds are mutagenous even in small doses and It is therefore an advantage if they can be avoided as far as possible.
A market has long existed for various types of filters suitable for purifying water from municipal pipes or private wells. However, traditional filters in the form of fine-meshed nets do not stop volatile substances like chorine and chlorinated hydrocarbons. Nor do filters containing ion-exchanging compounds (e.g. softeners) achieve this.
For this reason filters containing active carbon are now frequently used. The drawback with active carbon is that it is difficult to know when the filter is full and in many investigations it has been ascertained that the active carbon can quickly lose its effect if the load unexpectedly increases, thereby being transformed to a refuge, nutrient supply and germination spot for bacteria and other pyrogens.
The carbon filter is thus often combined with other methods to a more complicated apparatus including pre-filters to stop coarse particles and organic material, lamps with ultraviolet light to kill bacteria and ion exchangers to attract ions. Such equipment is relatively expensive and only functions satisfactorily if the coarse filters, ultraviolet lamps, ion-exchanging compound and active carbon are carefully changed. An alternative to these multi-step filters has also been developed that is based on distillation and reverse osmosis. However, none one of these per se advanced methods removes chlorine and chlorinated hydrocarbons entirely efficiently, and must be supplemented by a final filter of active carbon. Although the load on this final filter is far less than on carbon filters in the multi-step filters mentioned earlier, it must still be changed regularly and the problem of overloading remains.
A simpler method of killing bacteria and also removing chlorine and chlorinated hydrocarbons, as well as other volatile substances from the water is to boil the water in a boiler or an open vessel. There are primarily three drawbacks with this simple method in comparison with those mentioned earlier. A considerable amount of water must be boiled away in order to be certain that the volatile pollutants have been removed, which first of all is a waste of water and secondly results in a concentration of any non-volatile pollutants that may be in the water. The third drawback is that the user does not know when a satisfactory result has been reached.
A considerable number of industrial methods have been developed to separate liquid from gas, gas from liquid and one gas from another gas. The most usual principle is the cyclone principle whereby a steam/gas/water mixture is centrifuged and the liquid is thus forced out of the mixture. A very similar principle is for the mixture to be led through a pipe with many bends, the liquid being stopped by devices of various shapes in the bends.
Surface-enlarging devices are also used so that the water/gas/steam mixture is sprayed or sprinkled onto large plates or allowed to run down large plates or some other type of arrangement having a large surface, such as steel wool or plastic pellets.
It is also possible to force a gas, such as air or nitrogen, through the mixture. This gas then drives off other gases in the mixture or draws them with it. Often a combination of these techniques is used.
A previously known liquid cleaner of this type is described in Swedish Patent No. 510 287, according to which water is heated in a small depression in the bottom of a jug. The water is forced upwardly through a riser open at the top and then falls down of its own accord when it is stopped by the lid of the jug. The jug also contains a plurality of alternately convex and concave discs of different diameter spaced relatively far apart (1.5–2.5 cm) along the riser.
This liquid cleaner functions well per se but it has been considered desirable to obtain an improved version through technical development, which will give more liquid per time unit at lower cost.